Modular systems are used in many applications to provide flexibility and facilitate repair, maintenance, and upgrades. In the telecommunications industry, it is common to provide a system chassis or back plane into which one or more modular components, such as printed circuit boards, may be inserted.
To facilitate the insertion and removal of such modular components, and to enable such components to be locked into place once installed, a variety of locking and ejection devices have been provided. In one approach, an “ejector” lever is provided. In a locked position, a cam portion of the lever arm extends into a detent in the chassis, locking the modular component securely into place. In an unlocked position, the cam portion does not extend into the detent, thereby making it possible to slide the modular component into or out of a position in the chassis.
FIG. 1A shows a frontal view of a chassis 100 configured to receive a modular component (not shown). The chassis 100 comprises a frame 102, the front of which is shown in FIG. 1A. The frame 102 is formed in such a way as to leave an opening 104 into which a modular component may be inserted. FIG. 1B shows a top sectional view of the chassis 100 in the plane indicated by the arrows “A” in FIG. 1A. FIG. 1B shows the frame 102 comprising a left detent 106 and a right detent 108, such as may be provided to receive the cam portion of the ejector lever described above.
FIG. 2A shows a typical prior art modular device 200. The modular device 200 comprises a modular component 202 having a face plate 230, a left ejector lever 204 attached to a left lever support 206 in a manner that permits the lever 204 to be rotated as indicated by the arrow 208 about an attachment point 210. The modular device 200 further comprises a right ejector lever 212 attached to a right lever support 214 in a manner that permits the lever 212 to be rotated as indicated by the arrow 216 about an attachment point 218. In the position shown in FIG. 2A, the ejector levers 204 and 212 are in an unlocked position and would not impede the insertion or extraction of the modular device 200 from a chassis, such as the chassis 100 of FIGS. 1A and 1B. FIG. 2B shows the levers 204 and 212 after they have been rotated into a locked position. In this locked position, the lever 204 can be seen to comprise a cam portion 220 and the lever 212 to comprise a cam portion 222. In one typical configuration, the cam portion 220 and cam portion 222 would in the position shown in FIG. 2B extend into a detent in the chassis frame, such as the detents 106 and 108 of FIG. 1B. The arrows in FIG. 2B show the direction in which the lever arms 204 and 212 would be rotated to return them to the unlocked position shown in FIG. 2A.
A problem that may arise with the above-described approach to locking a modular component into a chassis or other frame is that the non-cam portion of the ejector lever arm may block access to a portion of the face plate of the modular component when the component has been installed and the lever arm(s) is(are) in the locked position. In FIG. 2B, for example, in the locked position shown the lever arms 204 and 222 block viewing of and access to portions of the face plate 230 of the modular component 202. As such, in the locked position the lever arms may interfere with the viewing of indicator lights or other displays, and may interfere with the removal or insertion of cables or modular subcomponents that the modular component 202 may be configured to receive, such as the swapping of media daughter access (MDA) modules in a network switch input/output (I/O) module installed in a network switch chassis.
Therefore, there is a need for a way to provide for the locking and ejection of modular components from a chassis that does not result in a lever arm or other structure being in a position that would block viewing of and/or access to the face plate of the modular component.